“Copied from: http://www.head-fi.org/t/686039/cosmic-ears-ba4f-review
I'm finding it hard to rate these, for the price I would give them 5 stars on every department. But I'd rather rate them, referenced with the idea of what the very best cIEM could be.
The BA4f with the Ice Blue color
Short History
Before I started my journey into the cIEM...” --Marleybob217

“First of all I'd like to say the customs and the cable are both insane, the customs look incredible and the linum cable and connector beat the hell out of any other CIEM I've seen around.
Cosmic Ears list this as a jack of all trades monitor which I do agree with. I'm coming from a 4BA model to this 2BA and I've been pleasantly surprised by the sound. I haven't had these a week yet so...” --daftpolecat

“First of all I'd like to say the customs and the cable are both insane, the customs look incredible and the linum cable and connector beat the hell out of any other CIEM I've seen around.
Cosmic Ears list this as a jack of all trades monitor which I do agree with. I'm coming for a 4BA model to this 2BA and I've been pleasantly surprised by the sound. I haven't had these a week yet so...” --daftpolecat

The HY2 combines a dynamic driver for lows and a balanced armature for the mids and highs. This dynamic driver also delivers an increased soundstage. The HY2 is a great sounding monitor for those looking for something a little different by combing the 2 driver technologies.
Twin hybrid – 1 for lows, 1 for mids and highs
Full sized medical grade hard acrylic shell
Various...

“The HY3 is a three-way, three-driver hybrid custom in-ear monitor from Sweden-based Cosmic Ears. It utilizes a dynamic driver for the bass and twin balanced armature drivers for the midrange and treble, which used to be a very rare configuration, although hybrids have increased in popularity over the past year. The bass unit looks to be around 8mm in diameter and has its own sound bore. The two...” --blueangel2323

The Pure model is the fantastic entry model to our range of customs yet it still has the benefits of custom in ear monitor.
The Pure fits perfectly to your ears, these high-quality headphones deliver a rich sound that off-the-shelf earbuds simply cannot match.

Developed by athletes, for athletes. Developed by an Ironman Triathlete and a 24-time marathoner, Yurbuds solve the problem athletes face wearing earphones. They don't hurt, and they are guaranteed to never fall out. Avid triathlete Seth Burgett, CEO of Yurbuds came up with the award-winning idea for custom fit earbud enhancers while participating in an Ironman competition. Yurbuds Earbud...

Developed by athletes, for athletes. Developed by an Ironman Triathlete and a 24-time marathoner, Yurbuds solve the problem athletes face wearing earphones. They don't hurt, and they are guaranteed to never fall out. Avid triathlete Seth Burgett, CEO of Yurbuds came up with the award-winning idea for custom fit earbud enhancers while participating in an Ironman competition. Yurbuds Earbud...

“I had a set of the Yurbuds Ironman earbuds before I purchased these hooking ones.
The locking ear cushion is comfortable and doesn't fall out when working out, playing ice hockey or riding my bike. All without the use of the hook.
I tried these behind the ear looping earphones simply because I wanted to after having success with the non-looping versions.
I returned...” --ShadowZ32